Bonded friction assembly



Aug. '27, 1946.

C. S. BATCHELOR BONDED FRICVTION ASSEMBLYI 4' t.Film June 1o, 1944- 2 Sheets-Sheet 1 Aug; 27, 1946. 5, BATCHELOR 1 2,406,653

- vBONDED FRIC'LION ASSEMBLY l Filed June 1o, 1944 2 sheets-snaai 2 Patented Aug. 27, 1946 BoNDED FRICTION ASSEMBLY Y Clyde lviatchelor, Nichols, Conn., assignor to Raybestosr-Manhattan, Inc., Passaic, N. J., a corporation of New Jersey f Application June 10, 1944,'Serial No. 539,657

9 claims. (o1. 18s-234) lThis invention relates" to improvements in friction assemblies such 'as brakes 'and clutches comprising a layer of friction material and a metallic or supporting mounting element therefor, and to the method of cementingo'r bondingi the friction material to the metallic supporting element.A

" It has heretofore -been proposed to bond or cefment brake linings or clutch facings/with their `'respective mounting ormetallic supporting elcments by meansl of adhesives'such as heat hardenable'synthetic resins for the purpose of avoiding or eliminating the necessity for `use of rivets,

or drilling, boring, or coun-terboringand registering the component parts; vor( with the end in. Yview of eliminating waste or portions of the"4 thickness of the friction material or for the prevention'of 'scoring of the mating .surfaces,"such as the brake drums, by Ameans 'of projecting rivets when the friction material or lining Ibecomes Vworn; or for the purpose of obtaining 'a 'better' union between the adjacent surfaces of the friction `material and the metallic mounting support so as to spread torsional stresses and also to induce more even mating and wear of the friction material.

The attempts or proposals to directly bond friction material such as'brake linings, conventionally composed of a densified hard composition of asbestos bers, mineral fillers anda heat hardenable binder, to the brake shoe by means ofa heat curable binder such as a synthetic resin, -has rendered'the normal removal and-replacement of the friction lining diiicult and at times detrimental to the metallic support and particularly when the attempt at removal and replacement-is to be carried out at a customary service station, since a conventional hard friction element or layer of friction material can only with diculty be removed by the expensive operations of grinding and chiseling entailing skillful labor andY time, and which always have the tendency to damage the brake shoe or other metallic mounting surface.

In order to render the operation of removal and replacement of bonded. brake linings less diicult and expensive, and to prevent injury of the metallic supporting surface, it has been pro- I posed in United States Patent No. 2,272,532 to bond brake linings to brake shoes by the intel'- position of one or more layers of a material sim-` ilar to that of which the brake lining is composed, that is, of asbestos, llers and a binder,

but of a relatively softer nature than thev hard and densed brake lining, that is, Va cleavable brake mung material coated with a. bestandenable resin, this material being separable 'along lines roughlyparallel'to itsfaces so as to permit it to be readily stripped or ground jfrom the brake shoe or band.

It will be readily apparent, however, that the very advantage ofjsuch proposal from a service standpoint is detrimental in applied usage, since f such cleavageplane presents a point o'f weakness during operation, particularly under high temperature, high speed 'andheavy duty operation resulting in failure from premature and undesirable vcleavage or separation.

In accordance with thepre'sent invention it is proposed to bond friction material 'such as brake linings, clutch facings or other clutch structural elements, composed 'of conventional hard, dense, formed frictionmaterial to brake shoes, clutch 'facings cone clutch element supports vand the` like, by means of a heat hardenable binder with the. attendantV advantages of a strong uniform bond and the 'elimination of conventional rivet-s, drilling and the like, and also avoidance Vof the detrimental effects of interposed, readily' cleavable materials or' compositions, in a manner which "at the same timepennits'separation of old or wornv friction materials from vtheir metallic mounting 'supports and the ready replacement thereof without the necessity rfor a high Vdegree of skill, excessive labor costs, and potential damage to metallic parts in such operation.

The objects of the present invention are in general accomplished by interposing between the surfaces of a friction element, such as aconventional pre-formed friction lining, c-lutch lfacing, or clutch structural element, and la metallic mounting or supporting element therefor, an invrterlayer composed of a relatively thin network,

web or sheet of cellulose fibres coated with a'heat hardenable bonding agent such as a synthetic resin, and subjecting the assembly to heat and pressure tofcure the resin and to bond the friction material to the metallic element, the curedk resin permeating `the interlayer and Vjoining the friction material to the metallic member. When occasion for replacement for the friction material arises, it may be separated from the metallic surface to which it is bonded by soaking the assembly in a caustic solution which penetrates and effects at least thecellulose of the interlayer, to cause material disintegration and swelling of the interlayer, to thereby render the friction material readily separable. i

' The invention, the method of carryingout the `liliV same, and the advantages thereof will be more tween the brake shoej. .I0l. andl.

' employment. bij.; ordnary'kraftfpeier- Athickness vof approximately'. .0.03.2V `p'air`1ted on both surfaces',w'ithgaI so "tiongof a heat hardenable phenolic resin, hasjbeen fo :d d

satisfactory, the ,pressuremand heat'curjingfopera- 50.

of a cone clutch assembly formed in accordance 1Q with my invention. Fig. 5 is a sectional view on the line 5-5 of Fig' 4 "1f El." .5 A.

Referring to the drawnigstlp cularlyK to 3, there is illustrated a coventioallbiakefslrioe 15` I0 having bonded thereto a brakelining II "by means of interlayer I2. The frictiorfmater'ial II may be of conventional brake lining composition such as asbestos, mineral fillers and a`h`eat hardleneclbinder and mayhave been cut fromy a'zroll 20 forhalve been supplied.. in theffrrn of. al shaped segr'nent"Thekinterlayerfv IZ jis'fQQITD s'ed ofv a permeablehnetwork or web of cellulose bresfsuch asyfor example afelted fibrous'sheetof paper.

The surfaces of the interlayerwlare coated,25 .by spraying, brusbinaeic., .Wthalba'i herd- .nablefbindersuches i011'. example a'thermQ-Sei- Ating syntheticf rr-isin. one example offsuch resin of` those commercially( a .ya'ilabilev "beingwfthe f phenolic Lresins.,fAfterfthe' assembly 'has been'go I 2Q interposed Abeformed.. that...s,lihe'i1.1 Sklave efbrakelining .I I,

the component vportions'are clamped together by means ofsuitable'cl'ampa'or other'vpressure deevices" or'pla'.tensfnotl illustrated,v andthe friction mterialbonded to .the brake.' slide. While 'apply- .l'ns 0r .maintaining 'preSSl'lre' throushfthefilidcated devices, by rneansjof` a' heat'sourfce .such

asy for example, radiant `h`e1at,`fdirect electrical resistance, steam heated`platens andfthe like'well known Vheating means,..tlepressureiand 'heat and degrees thereof4 being appuedjrera priodlof'ume Y suincient to' bond 'theipom'xnents 'ntden astion causingthe binder to, penetratethefinterlayer and` to bond; the'fric'tion materialfft'o' the metallic element therethrough, andto thus. gdey stroy any inherent cleavage properties'bf theginterlayer. While, thew'resultngfirrn. bon'dpre- 55` vents vready removalforfseparationfof"'tlie. layer of'. friction "materiallfrom [the 'metallic VVsii'ppfofi't, it. of course also preventsfanyfoperativelsurface failure by reason of premature cleavage or'sep- H aration.

is attacked by a causticsolutionand swells maabout ..3 *t0 5 hours. in "a1tr0fie-,eusiie.solution such as for example alodium hydroxide solution. Although it is irnpossible:tolapprrec bly .attack Curedlesin Smiles the.. pheuoli resins, 7o l.with caustic, when theresinis'a `continuoivls form, it is believed thatin accordancewiththe present invention .Sugli resin. is, .degree ab tacked by the..strdrl1g.peusiie ,.slollitpn .by reason.

lentf'ii-ivenntionftlie '45 further induces swelling. of .thecellulose to exert ..."afwedging. action between the. friction material and the metallic support, all of which permits `the Vfriction material or lining II to be readily ,l removed or Y split olf from the brake shoe I0 by inserting a'tool between the adjacent faces of thebrake shoe.v l0 and the lining II, without, .vQldovveverg:necessitating the use of force to a de- ,gree `which;would tend to damage the surface y ofthe brake shoel or requirement for finish grinding lto a' degreewhich would be necessary if the liningdl had been directly bonded to the shoe I in the absence of the caustic disintegratable interlayer or linerv I2. l.

In accordancefwith the present' .invefr'iy on..it has been further found. that .whenthepaper'or other cellulose web, of which the interlayer I2`.is formed Ais thinner than .001 i'r'1c`h. the. re'Sinor other bonding agent penetrates .so .thoroughly from both surfaces that the material will tegrate very slowlyif at all in aaustic so ut'io'n. On the other hand, whentheinterlayer is thicker than about .005 inch, lpenetration' .is'isucient and some traces of.a .cleavage pla'nemayfbe pres- .ent in the intermediate Zone( 'Betweenltheseapproximate limitations a rmbond may'be obtained which does'. not "exhibit'any planes'of cleavage during the.. most critical.v conditions. of usage but whichneverthelss maybe weakened and softened -to permit .separation by attack'cf a caustic solutionon the. interlayerandparticu- .larly the cellulose libres.. thereof whenv itf'is desi'red to remove and replace.'thefriction'niaterial.

Figs. .4'. and .5'.illustratefanother form of.. friction assemblyand morsp'ecicallyla particular @form of clutch assemblywherein employrnnftis .made (of. a `,co'n`fclutch structuralfelei'ent .I A3''in the formlof'ahellow 'regulartruncatedfconehaving a relativelythickened wall,"compos'ed'ofV a ventio'nalv friction material lmineral 'fille'rs-- The clutch element I3 is.V supported byQmeans' of la supportingl plate I4 ladapted to be= .secured ytothe flange of a .shaft suchas a crank "shaft,Y The plateld is .provided` with `arelatively narrow coiled rim le; .the clutch eiementple being joined to .theface ofthe conedfrimrIf-i by `meansmlofian Virfiterlayer I6, thelayer I6 being of .av similarer like nature to the interlayer I2 previously described.

Y In like manner .the cone clutchelementd may loe-joined tothe Vrim I5 ofthe supporting plate I4 bythe application of suitablelheat and pressure in V.the manner previously indicated Ywith respect to Figs. l and 3, to bond the friction material, I3 to the surface of the metallic support I5. to form a firmly bonded structure suitable fcnuse as a driving or driven member capable of transmitting torque.,

Althoughin the 'foregoing .two forms .of frictionassemblyl have.. been .illustrated it'. will., be readily, understood that other .forms iof.. friction assembly may be employed forautomotiveoriirlvdustrial l,uses and formed .accordance with .the .present invention wherein. pre-formed friction .materiaL is.,to .be .joined .to almetallic vmounting ,surface by meansof a .firm bond', butwhich `bond ofthe fact; thatthe resin penetrates a network 75 is disintegratable for replacement purposes so as to enable ready separation of the friction material from the metallic support when occasion requires.

I have referred specifically to synthetic resins in the foregoing specification as an example of a good type of bonding material for coating the cellulose strip. The invention in its broad aspects is not restricted to the use of synthetic resin as the bonding material but in its broad aspect embraces any bonding material which will form a satisfactory bond at temperatures between about 200 F. and about 400 F. and Which will not be destroyed at abnormal service ternperatures of say 550 F. at the bond. Thus, in addition to the phenol-formaldehyde type of resin hereinbefore discussed, I may use other synthetic resins as well as other binders, including the Vinylites, Bunas, neoprenes, resin-oils and the like. The terms heat hardenable, heat setting and heat curing as used in the speciiication and claims are intended to embrace binders of the foregoing type.

The principal vitalizing feature of the present invention is the provision of an intermediate bonding element comprising a relatively thin network of cellulose fibers.

I claim as my invention:

1. A friction assembly comprising a friction element, a metallic supporting element therefor and an intermediate bonding element comprising a network of cellulose bres having a thickness of from about .G01 to about .005 inch permeated with a cured resin.

2. A friction assembly comprising a layer of formed friction material in adhesive'bonded engagement with the surface of a metallic supporting element and an intermediate cellulosic fibre web having a thickness of from about .001 to about .005 inch permeated with a heat hardened binder.

3. A friction assembly comprising a layer of formed friction material, a metallic supporting and mounting element therefor, and an intermediate sheet of felted cellulose bres having a thickness of from about .001 to about .005 inch, the friction element being bonded to a surface f5 of the metallic element by means of a synthetic resin permeating the intermediate sheet.

4. A friction assembly comprising a layer of formed friction material in bonded engagement with the surface of a metallic mounting and supporting element, and an intermediate layer comprising a network of cellulose libres having a thickness of from about .001 to about .005 inch.

5. A friction assembly comprising a layer of formed friction material in bonded engagement with the surface of a metallic mounting and supporting element, and an intermediate layer cornprising a network of cellulose fibres having a thickness of approximately .003 inch.

6. A friction assembly comprising a layer of formed friction material, a metallic mounting and supporting element therefor, and an interlayer of cellulose bres having a thickness of from about .001 to about .005 inch, the friction material being bonded to the surface of the metallic element by means of a heat cured synthetic resin permeating the cellulose fibre interlayer.

'7. A friction assembly comprising a brake shoe, a brake lining, and an interlayer of cellulose fibres having a thickness of from about .001 to about .005 inch, the brake lining being bonded to the shoe by means of a synthetic resin heat cured in place and permeating the interlayer,

8. A friction assembly comprising a clutch element of formed friction material, a metallic mounting element therefor, and an interlayer of cellulose bres having a thickness of from about .001 to about .005 inch, the clutch friction element being bonded to a surface of the metallic mounting element by means of a synthetic resin heat cured in place and permeatin'g the interlayer.

9. A friction assembly comprising a friction element, a metallic supporting element therefor and an intermediate bonding element comprising a network of cellulose fibres having a thickness of from about .001 to about .005 inch and a heat hardenable binder.

CLYDE S. BATCHELOR. 

